Filter

ABSTRACT

A high temperature filter and a self-cleaning filtering system for filtering media, such as biomass materials, are provided. The filter and filtering system is particularly useful in the filtration of syngas in a plasma arc gasification process to remove char and other particles of down to a submicron size from the syngas. The filter is formed from a pleated metal mesh material including end caps secured by a high-temperature metallic paste or adhesive, such that the filter is capable of withstanding operating temperatures up to 2000° F. The system includes a backflush unit for injecting cleaning media therein to remove trapped char and other debris from the filter. At least two filtering systems can be placed in parallel so that one system can be cleaned while the other is operating. A method for filtering media is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon U.S. Provisional Patent Application Ser.No. 61/329,762 entitled “Filter”, filed Apr. 30, 2010 which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a filter and filtering system for filteringmedia and, more particularly, to a high temperature filter and aself-cleaning filtering system for filtering synthetic gas (syngas) in agasification process.

2. Description of Related Art

In the synthetic gas (syngas) industry, it is known that any debris in asyngas system made from biomass will harm the catalyst used in thereaction process. Therefore, it is necessary to filter the syngas toremove this char and other particles typically found therein. Due tohigh temperature processing conditions, current gasification systems usefilters formed from ceramic materials or tri-sintered metal. The use ofthese types of filters is often unsatisfactory, as ceramic filters cancrack and sintered metal filters cannot be easily cleaned to remove thefiltered particles therefrom. Additionally, ceramic material cannot beeasily recycled. Therefore, the filters are often discarded after aparticular period of time or after a particular number of filteringcycles. This discarding of the filters results in increased industrialwaste and causes processing downtime during replacement.

Different methods and systems for filtering biomass or syngas materialsare shown, for example, in U.S. Pat. Nos. 7,300,481; 7,056,487;6,077,490 and 4,865,627.

There is a need in the art for a high temperature filter andself-cleaning filtering system that can sufficiently remove char andother particles from a media, such as biomass material, with a minimumamount of processing downtime that overcomes the disadvantages of theprior art.

SUMMARY OF THE INVENTION

According to one aspect, the present invention is directed to a filterfor use in a gasification system such as in the production of syntheticgas or syngas. The filter can be formed from all stainless steelmaterials which can be easily cleaned and are readily recyclable intoscrap material. The filter comprises a cylindrical member formed from apleated metal mesh sheet having a first end portion and a second endportion. The pleated metal mesh sheet is overlapped and secured along atleast one edge portion to hold the sheet in a cylindrical shape. Atleast one end cap is positioned adjacent to at least one of the firstend portion and the second end portion. A high temperature metallicpaste or adhesive secures at least one end cap to at least one of thefirst end portion and the second end portion. The pleated metal sheet iswelded along the overlapped edge portion to form a weld line, and themetal paste can be applied along the weld line. According to oneembodiment, the at least one end cap comprises a first end cap and asecond end cap and the metallic paste or adhesive can also be used tosecure the first end cap to the first end portion of the cylindricalmember and to secure the second end cap to the second end portion of thecylindrical member. This metallic paste or adhesive can be capable ofwithstanding an operating temperature up to 2000° F. such as within therange of a 600-2000° F. or even the range of 1500-2000° F. One type ofmetallic paste that can be used is a high temperature epoxy resin.According to one embodiment, the metal mesh sheet is capable offiltering particles as small as 1 micron. According to anotherembodiment, the metal mesh sheet can be a metal cloth capable offiltering submicron sized particles.

According to another aspect, the present invention is directed to aself-cleaning filtering system for use in a gasification processcomprising a housing, a filter located within the housing, an inlet influid communication with the housing and filter for feeding a supply ofmedia therein for filtration, an outlet in fluid communication withand/or in cooperation with the filter for removing the filtered media, abackflush unit located inline between the filter and the outlet forinjecting or backflushing cleaning material back into the filter andremoving collected debris from the filter, and a drain in fluidcommunication with the housing for draining the debris as it is removedfrom the filter. The system can further include a vent for venting gasfrom within the housing. The cleaning material can be compressed air,steam, compressed gas, and liquid. One example of the cleaning materialcomprises the application of jet-air pulses. The supply of media can bea biomass material, which can be a liquid, such as water or oil, a gas,and/or a combination thereof. According to one embodiment, the media cancomprise syngas and the filter can be configured for removing char andparticles having a submicron size from the syngas. The filter can be acylindrical pleated metal mesh filter. Also, the filter can be securedtogether with a high temperature metallic paste or adhesive and iscapable of withstanding operating temperatures up to 2000° F. such aswithin the range of a 600-2000° F. or even the range of 1500-2000° F.The filtering system can be arranged in a simplex or a duplex design. Inthe duplex design, at least two filtering systems are placed in parallelso that at least one of the filtering systems remains in operation whilethe other system is being cleaned.

According to yet another aspect, the invention is directed to a methodfor filtering a syngas in a gasification system. The method comprisesproviding a housing, positioning a filter within the housing, feeding asupply of syngas into the housing and the filter for filtration thereof,and providing an outlet in fluid communication with and/or incooperation with the filter for removing the filtered syngas material.The filter is capable of filtering submicron particles at high operatingtemperatures. The filter can comprise a metal mesh pleated cylindricalfilter having a pair of end caps attached to the filter with a hightemperature metallic paste or adhesive, such as an epoxy, e.g.,Loctite®. The filter can be capable of withstanding operatingtemperatures up to 2000° F. such as within the range of a 600-2000° F.or even the range of 1500-2000° F. The method can further includeproviding a backflush unit located inline between the filter and theoutlet for blowing cleaning media back through the filter to dislodgecollected particles from the filter and providing a drain in fluidcommunication with the housing for draining the particles as they areremoved from the filter. The method can also include providing a vent incooperation with the housing for venting excess gas from within thehousing.

These and other features and characteristics of the present invention,as well as the methods of operation and functions of the relatedelements of structures, and the combination of parts and economies ofmanufacture, will become more apparent upon consideration of thefollowing description with reference to the accompanying drawings, allof which form a part of this specification, wherein like referencenumerals designate corresponding parts in the various figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional side elevation view of the filter,according to the invention, for use in the gasification process;

FIG. 2 shows a top view of the filter of FIG. 1;

FIG. 3A shows an exploded view of the filter portion denoted by IIIA inFIG. 2;

FIG. 3B shows an exploded view of the filter portion denoted by IIIB inFIG. 3A;

FIG. 4 shows a cross-sectional side elevation view of a simplexself-cleaning filtering system, including the filter of FIG. 1, for usein a gasification process;

FIG. 4A shows a chart depicting the valving arrangement for thefiltration of a gas through the filtering system of FIG. 4;

FIG. 4B shows a chart depicting the valving arrangement for thefiltration of a liquid through the filtering system of FIG. 4;

FIG. 5 shows a side elevation view of a duplex self-cleaning filteringsystem, including the filter of FIG. 1, for use in a gasificationprocess;

FIG. 5A shows a chart depicting the valving arrangement for thefiltration of a media through the filtering system of FIG. 5;

FIG. 6 shows a top view of the duplex filter system of FIG. 5;

FIG. 7 shows a side elevation detailed view of the inlet/outlet manifoldof the filtering system of FIG. 5;

FIG. 8 shows a chart depicting various micronic filter clothspecifications which can be used for the metal mesh material of thefilter of FIG. 1; and

FIG. 9 shows a chart depicting various specifications for Twill Dutchweave filter cloth which can be used for the metal mesh material of thefilter of FIG. 1.

BRIEF DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal”, and derivatives thereof, shall relate to the inventionas it is oriented in the drawing figures. However, it is to beunderstood that the invention may assume various alternative variations,except where expressly specified to the contrary. It is also to beunderstood that the specific devices illustrated in the attacheddrawings, and described in the following specification, are simplyexemplary embodiments of the invention. Hence, specific dimensions andother physical characteristics related to the embodiments disclosedherein are not to be considered as limiting.

Reference is now made to FIGS. 1-2, which show the filter according tothe invention, generally indicated as 10, for use in a gasificationprocess for filtering media, such as biomass materials or wastematerials, such as a synthetic gas or syngas in a plasma arcgasification system. The filter 10 can be formed from all stainlesssteel materials. The use of an all stainless steel filter facilitatesthe physical cleaning of the filter so that the filter can be easilyrecycled as scrap metal. The filter 10 can comprise a cylindrical member12 formed from a pleated metal mesh 14 sheet having a first end portion16 and a second end portion 18. According to one embodiment, the filter10 can be pleated into multiple pleats having multiple pleat depths sothat a variety of filters having a variety of surface areas can beproduced. In order to increase the amount of surface area, the filtersare designed to be stackable upon one another. The pleated metal meshsheet 14 is overlapped, as shown at 23 in FIG. 3A, and secured along atleast one edge portion to hold the sheet 14 in a cylindrical shape. Atleast one end cap or a pair of end caps, such as a first end cap 20 anda second end cap 22, can be secured to the cylindrical member 12. Astructural plate 28 can be provided substantially midway between thefirst end portion 16 and the second end portion 18 or at any otherlocation as needed for supporting the cylindrical member 12. Asillustrated in FIG. 3B, the filter 10 can comprise a plurality of metalmesh sheets 14 a, 14 b and 14 c, and a perforated sheet metal layer 15to provide support and strength to the metal mesh sheets 14 a, 14 b and14 c.

A high temperature metallic paste can be used to secure the end caps 20,22 to at least one of the first end portion 16 and the second endportion 18. The pleated metal sheet 14 can be welded along theoverlapped one edge portion 23 to form a weld line 24 as shown in FIG.3A and the high temperature metallic paste can also be applied, as shownby 26 in FIG. 3A, along the overlap having a length L such that themetallic paste encompasses the weld line 24. The purpose for theapplication of the metallic paste along entire length L of the overlapis to seal off this overlap and to fill any voids which may have beencreated during welding. The metallic paste is of a formulation that iscapable of withstanding an operating temperature within the range of upto 2000° F. such as 600-2000° F. or even within the range of 1500-2000°F. The filter 10 is designed for filtering up to a 20 psid(differential). The metallic paste can be Loctite® Fixmaster® 2000°Putty, produced by the Henkel Corporation, which is an epoxy singlecomponent putty designed to fill and restore damaged metal and fillcracks in environments that will see temperatures up to 2000° F. Thispaste is water-based, non-toxic and a self-reactive cure type.

According to one embodiment, the metal mesh sheet 14 is capable offiltering particles as small as 1 micron. According to anotherembodiment, the metal mesh sheet can be a metal cloth capable offiltering submicron sized particles. Examples of the different types ofmetal sheet and/or cloth material are shown in FIGS. 8 and 9. FIGS. 8and 9 show Twill Dutch Weave Filter Cloth. The term “Twill” refers to aweave wherein the warp and weft (shute) wires pass alternately over twoand under two wires. The term “Dutch” refers to the use of a heavierwarp wire diameter in conjunction with a lighter weft wire diameter. Ina Twill Dutch Filter Weave, the weft wires are driven up so tightly thatthere is always a shute wire above and below the warp wires, creating aweave with the warp wires completely covered. The flow-pass geometry isextremely tortuous, allowing reasonable flow rates while insuringexcellent particle size retention.

Reference is now made to FIG. 4, which shows a cross-sectional sideelevation view of a self-cleaning simplex self-cleaning filteringsystem, generally indicated as 50, including the filter 10 describedabove and shown in FIG. 1, for use in a gasification process. Thefiltering system 50 comprises a housing 52, the filter 10, locatedwithin the housing 52, and an inlet 56 for feeding a supply of mediainto the housing 52 and the filter 10 for filtration thereof. The system50 further includes an outlet 58 in cooperation with the filter 10 forremoving the filtered media and a backflush unit 60 located inlinebetween the filter 10 and the outlet 58 for injecting or backflushingcleaning material back into the filter 10 and removing collected debris,such as char, from the filter 10. An opening 62 is located in fluidcommunication with the housing 52, such as at the bottom 64 of thehousing 52, for draining the debris through drain 66 as it is removedfrom the filter 10. The system 50 can further include a vent 68 forventing gas from within the housing. The cleaning material can becompressed air, steam, compressed gas, liquid, and the like. One exampleof the cleaning material comprises a thirty second jet-air pulse toremove the char and debris that is collected on the filter element 10.The supply of media can be a biomass material and can be a liquid, suchas water or oil, a gas, and/or a combination thereof. According to oneembodiment, the media can comprise syngas and the filter 10 can beconfigured for removing char and particles having a 1 micron sized, oreven as small as submicron sized, particles from the syngas. Asdiscussed above, and shown in FIG. 1 the filter can be a cylindricalpleated metal mesh filter having the particular weaves shown in thetables of FIGS. 8 and 9. FIGS. 4A and 4B show the operation of thefiltering system 50, including the opening and closing of the inlet 56,outlet 58, backflush unit 60 and drain 66, during the filtration of agas and liquid respectively, during standard filtering operation,venting, and backflushing. It can be appreciated that inlet 56, outlet58, backflush unit 60 and drain 66 can be located at any location withrespect to the housing 52, as long as they are in fluid communicationwith the housing. Flow through the inlet 56, outlet 58, backflush unit60 and drain 66 can be controlled, for example, by valves as shown by57, 59, 61 and 67 in FIG. 4.

As shown in FIGS. 5-7, the filtering system can be a duplex design,generally indicated as 70. In the duplex design, at least two filteringsystems, such as a first filtering system 72 and a second filteringsystem 74, are placed in parallel so that at least one of the filteringsystems 72, 74 remains in operation while the other system is beingcleaned. The duplex system 70 also includes a pair of inlets 102, 104for feeding the media into the respective first and second housings 71A,71B and subsequently into first and second filters 73, 75, and a pair ofoutlets 94, 96 in fluid communication with first and second housings71A, 71B respectively. An inlet/outlet manifold 76 is positioned in-linebetween the first and second filtering systems 72, 74. As illustrated inFIG. 7, the inlet/outlet manifold 76 includes a baffle plate 77 todirect the inlet flow of the media to either the first filtering system72 or second filtering system 74 depending upon which of the valves 1Aor 1B are open. The inlet flow then moves throughout the designatedfirst or second filtering system 72, 74. After filtration is completed,the filtered media then re-enters the inlet/outlet manifold 76 and comesinto contact with baffle plate 77 which prevents the filtered media fromre-entering into the first or second filtering systems 72, 74 anddiverts the filtered media through the outlet and out of the duplexsystem 70.

During cleaning of one of the filtering systems 72, 74, certain valvesassociated with that particular system to be cleaned start closing (e.g.1A, 2A, 1B, 2B) while other valves, directly associated with arespective filter 73, 75 (e.g. 4A and 4B), are opened and closed on anintermittent schedule and the respective valve associated with drain 92(e.g. 3A and 3B), is opened, while introducing a back purge via firstand second backflush units 78 or 80 to dislodge the debris from thefilter media so that this debris is discharged out the first and/orsecond bottom drain 82, 84, respectively. First and second vents 86, 88may be provided to vent any excess gas from the filtering systems 72,74. FIG. 5A shows the operation of the duplex filtering system 70,including the opening and closing of the various valves 1A-4A and 1B-4Bduring the filtration of a media, during no-flow, start-up operation,dwell and backflush. It can be appreciated that the media can be anytype of material to be filtered, including water, oil, gas, and thelike.

As stated above, this duplex arrangement 70, as shown in FIGS. 5-7,ensures that the system functions in a continuous manner. The duplexhousing arrangement 70 will switch from one housing 72 to the other 74,upon a 15 psid differential, then a cleaning process will be activated,for example, a cleaning process using a 30 second Jet-Air Pulse, via abackflush unit 78, 80 to remove the debris on the filter element 10,which is then blown down through the cone bottom 89, 90 of the housing,through drains 82, 84 and subsequently out of the system via drain 92,thus discharging the filtered char from the surface of the filter 10.

According to another aspect, the invention is directed to a method forfiltering a media, such as a syngas, in a gasification system. Withcontinuing reference to FIG. 4, the method comprises providing a housing52, positioning a filter 10 within the housing 52, feeding a supply ofmedia into the housing 52 and the filter 10 for filtration thereof, andproviding an outlet 58 for cooperation with the filter 10 for removingthe filtered material. The filter 10 is capable of filtering submicronparticles at high operating temperatures up to 2000° F., such as withinthe range of 600-2000° F. or even the range of 1500-2000° F. As shown inFIGS. 1-2, 3A, 3B and 4, and discussed above, the filter 10 can comprisea metal mesh pleated cylindrical filter member 12, including a pair ofend caps 20, 22 attached to the filter 10 with a high temperaturemetallic paste or adhesive. The method can further include providing abackflush unit 60 located inline between the filter 10 and the outlet 58for introducing cleaning media back through the filter 10 to dislodgecollected particles and char from the filter 10. The method alsoincludes providing an outlet or drain 62 in the housing and a drainoutlet 66 for draining the particles out of the housing 52 as they areremoved from the filter 10. The method can also include providing a vent68 cooperating with the housing for venting excess gas from within thehousing. The above-described method can also be performed using theduplex system, as shown in FIGS. 5-7, so that the system functions in acontinuous manner during cleaning, thus eliminating downtime during theprocessing of the media.

It can be appreciated that the syngas filtration process system of theinvention can be used on any type of media or biomass syngas, includingmunicipal solid waste (MSW), waste food, glycerin, wood chips, cropwaste, coal gasification (IGCC), and the like.

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of this description. For example, it is to be understood that thepresent invention contemplates that, to the extent possible, one or morefeatures of any embodiment can be combined with one or more features ofany other embodiment.

1. A filter for use in a gasification system in the production ofsyngas, said filter comprising: a cylindrical member formed from apleated metal mesh sheet having a first end portion and a second endportion, said pleated metal mesh sheet being overlapped and securedalong at least one edge portion to hold the sheet in a cylindricalshape; at least one end cap positioned adjacent to at least one of thefirst end portion and the second end portion; and a high temperaturemetallic paste or adhesive for securing the at least one end cap to theat least one of the first end portion and the second end portion.
 2. Thefilter of claim 1, wherein the pleated metal sheet is welded along theat least one edge portion to form a weld line.
 3. The filter of claim 2,wherein the metallic paste or adhesive is applied along the weld line.4. The filter of claim 1, wherein the at least one end cap comprises afirst end cap and a second end cap and wherein the metallic paste oradhesive is used to secure the first end cap to the first end portion ofthe cylindrical member and the second end cap to the second end portionof the cylindrical member.
 5. The filter of claim 1, wherein themetallic paste or adhesive is capable of withstanding an operatingtemperature up to 2000° F.
 6. The filter of claim 5, wherein themetallic paste or adhesive is capable of withstanding an operatingtemperature within the range of 600-2000° F.
 7. The filter of claim 6,wherein the metallic paste or adhesive is capable of withstanding anoperating temperature within the range of 1500-2000° F.
 8. The filter ofclaim 1, wherein the metal mesh sheet is capable of filtering particlesas small as 1 micron.
 9. The filter of claim 1, wherein the metal meshsheet is a metal cloth capable of filtering submicron sized particles.10. The filter of claim 1, wherein the metallic paste or adhesivecomprises an epoxy based resin.
 11. The filter of claim 1, wherein themetal mesh sheet and the at least one end cap is formed from a stainlesssteel material.
 12. A self-cleaning filtering system for use in agasification process, said filtering system comprising: a housing; afilter located within the housing; an inlet for feeding a supply ofmedia into the housing and the filter for filtration thereof; an outletin cooperation with the filter for removing the filtered media; abackflush unit located inline between the filter and the outlet forinjecting cleaning material back into the filter and removing collecteddebris from the filter; and
 13. a drain in fluid communication with thehousing for draining the debris as it is removed from the filter. Thesystem of claim 12, further including a vent for venting gas from withinthe housing.
 14. The system of claim 12, wherein the cleaning materialis selected from the group consisting of compressed air, steam,compressed gas, and liquid.
 15. The system of claim 14, wherein thecleaning material comprises jet-air pulses.
 16. The system of claim 12,wherein the supply of media is selected from the group consisting ofliquid, gas, and a combination thereof.
 17. The system of claim 12,wherein the filter comprises a cylindrical pleated metal mesh filter.18. The system of claim 17, wherein the filter is secured together witha high temperature metallic paste or adhesive and wherein the metallicpaste or adhesive is capable of withstanding operating temperatures upto 2000° F.
 19. The system of claim 18, wherein the metallic paste oradhesive is capable of withstanding an operating temperature within therange of 600-2000° F.
 20. The system of claim 19, wherein the metallicpaste or adhesive is capable of withstanding an operating temperaturewithin the range of 1500-2000° F.
 21. The system of claim 12, whereinthe media comprises syngas and the filter is configured for removingchar and particles having a submicron size.
 22. The system of claim 12,wherein at least two filtering systems are placed in parallel so that atleast one of the filtering systems remains in operation while the otherfiltering system is being cleaned.
 23. A method for filtering a syngasin a gasification system, said method comprising providing at least afirst filtering system comprising: providing a housing; positioning afilter within the housing; feeding a supply of syngas into the housingand the filter for filtration thereof; and providing an outlet incooperation with the filter for removing the filtered syngas wherein thefilter is capable of filtering submicron particles at high operatingtemperatures.
 24. The method of claim 23, wherein the filter comprises ametal mesh pleated cylindrical filter and a pair of end caps attached tothe filter with a high temperature metallic paste or adhesive.
 25. Themethod of claim 24, wherein the filter is capable of withstandingoperating temperatures up to 2000° F.
 26. The method of claim 25,wherein the filter is capable of withstanding an operating temperaturewithin the range of 600-2000° F.
 27. The method of claim 26, wherein thefilter is capable of withstanding an operating temperature within therange of 1500-2000° F.
 28. The method of claim 23, including providing abackflush unit located inline between the filter and the outlet forblowing cleaning media back through the filter to dislodge collectedparticles from the filter; and providing a drain in the housing fordraining the particles as they are removed from the filter.
 29. Themethod of claim 23, including providing a vent cooperating with thehousing for venting excess gas from within the housing.
 30. The methodof claim 23, wherein the method includes providing at least a secondfiltering system in parallel operation with the first filtering systemso that cleaning of either the first or second filtering system canoccur while the opposite filtering system is operating.